Giant enhancement of negative friction by resonant coupling between localized surface phonon polaritons and graphene plasmonics

Negative friction refers to a frictional force that acts in the same direction as the motion of an object, which has been predicted in terahertz (THz) gain systems Phys. Rev. B108 045406 (2023). In this work, we investigate the enhancement of the negative friction experienced by nanospheres placed near a graphene substrate. We find that the magnitude of negative friction is related to the resonant coupling between the surface plasmon polaritons (SPPs) of the graphene and localized surface phonon polaritons (LSPhP) of nanospheres. We exam nanospheres consisted of several different materials, including SiO₂, SiC, ZnSe, NaCl, lnSb. Our results suggest that the LSPhP of NaCl nanospheres match effectively with the amplified SPPs of graphene sheets. The negative friction for NaCl nanospheres can be enhanced about one-to-two orders of magnitude compared to that of silica (SiO₂) nanospheres. At the resonant peak of negative friction, the required quasi-Fermi energy of graphene is lower for NaCl nanospheres. Our finds hold great prospects for the mechanical manipulations of nanoscale particles.